Earlier this week we took at look at some great free web based alternatives to Photoshop. Since we don't always have web access (this can be especially true during our favorite photo editing time: while riding on a plane), we decided it was a good idea to look at some free photo editing options available for download.

In this list we've broken our software down just like we had with our web based list. Basic applications will perform basic photo editing tasks like cropping and resizing, while the More Robust applications will be more akin to Photoshop with options such as working with layers. Applications built for the Mac will have an "M" at the end, Windows a "W," Unix a "U."

Basic

iPhoto: Since iLife comes free on every Mac, it makes our cut for a decent free basic photo editor. Of course iPhoto also boasts great photo organization in addition to the simple editing. M

PhotoFiltre: This simple editor is like a pared down Photoshop and would have made our More Robust category had it included layer support. W

Picasa: Think of this software as Google's answer to iPhoto mashed with Flickr. M, W

PhotoPlus: Yet another basic photo editor, bonus for the lay users, this one comes with a tooth whitener tool. W

Photoscape: This basic photo editor allows for RAW conversions to JPEG and has a tool for creating animated GIFs. W

More Robust

Gimp: Easily the most popular free robust Photoshop replacement, and it is easy to see why. With an amazing array of editing tools and thriving developer community, Gimp is a fantastic choice for a real Photoshop replacement and is the one we most frequently use here at Unplggd. M, U, W

LiveQuartz: This easy to use editor has a surprising amount of tools including layer management and multi-touch support. M

Seashore: Another open source editor, Seashore, features gradients, textures, and anti-aliasing for both text and brush strokes.

Paint.Net: Originally intended as a free replacement to Microsoft Paint software, Paint.Net has grown over the years into a much more powerful tool that includes layer support and several editing tools. W

Pixen: This open source editor is designed specifically for pixel artists and features elegant layer support and great animation tools. M